DIAGNOSIS The air fryer lid has a separate heating element and thermal fuse. No heat means the element circuit is open, often from the fuse blowing.
FIX Unplug the lid from the main unit. Inspect the four power/communication pins on the lid connector for bending or debris. Clean them with a dry cloth. Reconnect firmly until it clicks. Try the Air Fry function again.
IF THAT DIDN'T WORK The heating element or its internal thermal fuse has failed. The entire air fryer lid assembly must be replaced. Contact Ninja support. User repair is not possible.
HEADS UP Never operate the air fryer lid without the inner pot and crisper plate in place. Running it empty or with a blocked airflow path can overheat and blow the fuse.